Field of the Invention
The present invention relates to a scintillator panel with reduced warpage of the panel itself and reduced crack formation in a phosphor layer, and also to a radiation detector using the scintillator panel.
Description of the Related Art
In recent years, clinical sites use, for diagnoses of disease conditions, radiation detectors that convert a radiation emitted from a radiation source and transmitted through an imaged site of the subject, into an electrical charge to generate a digital radiological image. Such radiation detectors are categorized into two groups: (1) those of a scintillator type, which each convert a radiation into visible light through a phosphor layer containing Gd2O2S, CsI, or other material, and then convert the light into an electrical charge by means of a photoelectric conversion device (PD), and (2) those of a type that each convert the X-ray directly into an electrical charge by means of an X-ray detection device, which is typically formed of Se. The scintillator type draws more attention.
As far as a radiation detector of a scintillator type is concerned, JP 2005-114456 A, for example, discloses a radiation detector that has in combination a scintillator panel and a photoelectric conversion device that uses a thin film transistor (TFT) and a charge-coupled device (CCD).
In order to meet market demand for smaller size, lighter weight, and/or wider variation of radiation detectors, materials having lighter weight, thinner thickness, and good workability are desired. A technique that uses a resin substrate as a substrate for supporting the phosphor has been proposed to meet these demands (JP 2012-47487 A).
However, when a highly flexible material such as a resin substrate is used, a difference in the linear expansion coefficient between a phosphor and a resin substrate presents a problem in that, due to heat generated during a manufacturing process and/or in a use environment, the scintillator panel warps, and is then separated from the photoelectric conversion device, or a crack develops in the phosphor to cause deterioration in image quality, for example.
In order to solve these problems, patent documents such as WO2011/010482 and WO2010/140410 disclose techniques to prevent warpage by attaching a warpage prevention resin film on a surface that is to face the resin substrate, of the phosphor layer, or by sandwiching the scintillator panel between a sensor substrate disposed on the photoelectric conversion device and a rigid plate made of a material similar to that of the sensor substrate. Nevertheless, a technology that controls warpage by the scintillator panel by itself has not been disclosed.